Liquid crystal display device

ABSTRACT

A liquid crystal display in which a first substrate includes a sub-pixel electrode extending in a first direction, and first and second main pixel electrodes connected with opposite ends of the sub-pixel electrode and extending in a second direction orthogonally crossing the first direction. A second substrate includes first and second sub-common electrodes arranged on both sides sandwiching the sub-pixel electrode, a first main common electrode connected with the first sub-common electrode and extending along the second direction opposite to the extending direction of the first main pixel electrode on one end side of the sub-pixel electrode, and a second main common electrode connected with the second sub-common electrode and extending along the second direction opposite to the extending direction of the second main pixel electrode on the other end side of the sub-pixel electrode.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromprior Japanese Patent Application No. 2011-097003, filed Apr. 25, 2011,the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a liquid crystaldisplay device.

BACKGROUND

In recent years, a flat panel display is developed briskly, andespecially, the liquid crystal display device gets a lot of attentionfrom advantages, such as light weight, thin shape, and low powerconsumption. Especially, in an active matrix type liquid crystal displaydevice equipped with a switching element in each pixel, a structureusing lateral electric field, such as IPS (In-Plane Switching) mode andFFS (Fringe Field Switching) mode, attracts attention. The liquidcrystal display device using the lateral electric field mode is equippedwith pixel electrodes and a common electrode formed in an arraysubstrate, respectively. Liquid crystal molecules are switched by thelateral electric field substantially in parallel with the principalsurface of the array substrate.

On the other hand, another technique is also proposed, in which theliquid crystal molecules are switched using the lateral electric fieldor an oblique electric field between the pixel electrode formed in thearray substrate and the common electrode formed in a counter substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention, andtogether with the general description given above and the detaileddescription of the embodiments given below, serve to explain theprinciples of the invention.

FIG. 1 is a figure schematically showing a structure of a liquid crystaldisplay device according to one embodiment.

FIG. 2 is a figure schematically showing the structure and theequivalent circuit of a liquid crystal display panel shown in FIG. 1.

FIG. 3 is a cross-sectional view schematically showing the liquidcrystal display panel including a switching element, etc.

FIG. 4 is a plan view schematically showing a structure of one pixel ona counter substrate constituting the liquid crystal display panelaccording to a first embodiment.

FIG. 5 is a plan view schematically showing a structure of the pixel onan array substrate in the liquid crystal display panel when the pixel isseen from the counter substrate side according to the first embodiment.

FIG. 6 is a plan view of one pixel showing an operation of the liquidcrystal display panel according to the first embodiment.

FIG. 7 is a figure schematically showing an example of a layout of anactive area according to the first embodiment.

FIG. 8 is a figure schematically showing a modification of the layout ofthe active area according to the first embodiment.

FIG. 9 is a plan view schematically showing the structure of one pixelon the counter substrate constituting the liquid crystal display panelaccording to a second embodiment.

FIG. 10 is a plan view schematically showing a structure of the pixel onthe array substrate in the liquid crystal display panel when the pixelis seen from the counter substrate side according to the secondembodiment.

FIG. 11 is a plan view of one pixel showing an operation of the liquidcrystal display panel according to the second embodiment.

FIG. 12 is a figure schematically showing a layout of the active areaaccording to the second embodiment.

FIG. 13 is a figure schematically showing a modification of the layoutof the active area according to the second embodiment.

DETAILED DESCRIPTION

A liquid crystal display device according to an exemplary embodiment ofthe present invention will now be described with reference to theaccompanying drawings wherein the same or like reference numeralsdesignate the same or corresponding parts throughout the several views.

According to one embodiment, a liquid crystal display device having aplurality of pixels, includes: a first substrate including; a sub-pixelelectrode extending in a first direction, a first main pixel electrodeconnected with one end of the sub-pixel electrode and extending in asecond direction orthogonally crossing the first direction, and a secondmain pixel electrode connected with the other end of the sub-pixelelectrode and extending in the second direction opposite to theextending direction of the first main pixel electrode, a secondsubstrate including; a first sub-common electrode and a secondsub-common electrode arranged on both sides sandwiching the sub-pixelelectrode, a first main common electrode connected with the firstsub-common electrode and extending along the second direction oppositeto the extending direction of the first main pixel electrode on one endside of the sub-pixel electrode, and a second main common electrodeconnected with the second sub-common electrode and extending along thesecond direction opposite to the extending direction of the second mainpixel electrode on the other end side of the sub-pixel electrode, aliquid crystal layer including liquid crystal molecules and held betweenthe first substrate and the second substrate.

FIG. 1 is a figure schematically showing the structure of the liquidcrystal display device 1 according to one embodiment.

The liquid crystal display device 1 includes an active-matrix typeliquid crystal display panel LPN, a driver IC chip 2 connected to theliquid crystal display panel LPN, a flexible wiring substrate 3, abacklight 4 for illuminating the liquid crystal display panel LPN, etc.

The liquid crystal display panel LPN is equipped with an array substrateAR as a first substrate, a counter substrates CT as a second substratearranged opposing the array substrate AR, and a liquid crystal layer(not shown) held between the array substrate AR and the countersubstrates CT. The liquid crystal display panel LPN includes an activearea ACT which displays images. The active area ACT is constituted by aplurality of pixels PX arranged in the shape of a (m×n) matrix (here,“m” and “n” are positive integers).

A backlight 4 is arranged on the back side of the array substrate AR inthe illustrated example. Various types of backlights can be used as thebacklight 4. For example, a light emitting diode (LED) or a cold cathodefluorescent lamp (CCFL), etc., can be applied as a light source of thebacklight 4, and the explanation about its detailed structure isomitted.

FIG. 2 is a figure schematically showing the structure and theequivalent circuit of the liquid crystal display panel LPN shown in FIG.1.

The liquid crystal display panel LPN is equipped with “n” gate lines G(G1-Gn), “n” auxiliary capacitance lines C (C1-Cn), “m” source lines S(S1-Sm), etc., in the active area ACT. The gate line G and the auxiliarycapacitance line C are arranged in parallel each other in a firstdirection X that perpendicularly intersects a second direction Y.However, they do not necessarily extend linearly. The source lines Sextend in the second direction Y that intersects the gate line G and theauxiliary capacitance line C in parallel. Though the source lines Sextend in the second direction Y, respectively, they do not necessarilyextend linearly. The gate line G, the auxiliary capacitance line C andthe source lines S may be crooked partially.

Each gate line G is pulled out to the outside of the active area ACT,and is connected to a gate driver GD. Each source line S is pulled outto the outside of the active area ACT, and is connected to a sourcedriver SD. At least a portion of the gate driver GD and the sourcedriver SD is formed in the array substrate AR, for example, and the gatedriver GD and the source driver SD are connected with the driver IC chip2 provided in the array substrate AR and having an implementedcontroller.

Each pixel PX includes a switching element SW, a pixel electrode PE, acommon electrode CE, etc. Retention capacitance Cs is formed, forexample, between the auxiliary capacitance line C and the pixelelectrode PE.

In addition, in the liquid crystal display panel LPN according to thisembodiment, while the pixel electrode PE is formed in the arraysubstrate AR, the common electrode CE is formed in the counter substrateCT. Liquid crystal molecules of a liquid crystal layer LQ are switchedmainly using an electric field formed between the pixel electrodes PEand the common electrodes CE. The electric field formed between thepixel electrode PE and the common electrode CE is a lateral electricfield substantially in parallel with the principal surface of the arraysubstrate AR or the principal surface of the counter substrate CT, or anoblique electric field slightly oblique with respect to the principlesurfaces of the substrates.

The switching element SW is constituted by an n channel type thin filmtransistor (TFT), for example. The switching element SW is electricallyconnected with the gate line G and the source line S. The (m×n)switching elements SW are formed in the active area ACT.

The pixel electrode PE is electrically connected with the switchingelement SW. The (m×n) pixel electrodes PE are formed in the active areaACT. The common electrode CE is set to a common potential, for example.The common electrode CE is arranged in common to the plurality of pixelelectrodes PE through the liquid crystal layer LQ. The auxiliarycapacitance line C is electrically connected with a voltage impressingportion VCS to which the auxiliary capacitance voltage is impressed.

The array substrate AR includes an electric power supply portion VSformed outside of the active area ACT. Furthermore, the common electrodeCE formed on the counter substrate CT is electrically connected with theelectric power supply portion VS formed in the array substrate ARthrough an electric conductive component which is not illustrated.

FIG. 3 is a view schematically showing the cross-section of the liquidcrystal display panel LPN including the switching element SW. Inaddition, only the portion required for explanation is illustrated here.

The backlight 4 is arranged at the back side of the array substrate ARwhich constitutes the liquid crystal display panel LPN.

The array substrate AR is formed using an insulating substrate 10 havinga light transmissive characteristics, such as a glass substrate and aplastic substrate. This array substrate AR includes the switchingelement SW, the pixel electrode PE, a first alignment layer AL1, etc.,on the side of the first insulating substrate 10 facing the countersubstrate CT.

In the example shown here, the switching element SW may be either atop-gate type switching element or a bottom-gate type switching element,and includes a semiconductor layer formed of poly-silicon or amorphoussilicon, though the detailed description thereof is not made.

The semiconductor layer SC has a source region SCS and a drain regionSCD on both sides which face across a channel region SCC, respectively.In addition, an undercoat layer which is an insulating film may bearranged between the first insulating substrate 10 and the semiconductorlayer SC. The semiconductor layer SC is covered with a gate insulatingfilm 11. Moreover, the gate insulating film 11 is arranged also on thefirst insulating substrate 10.

The gate electrode WG of the switching element SW is formed on the gateinsulating film 11, and is located on the channel region SCC of thesemiconductor layer SC. The gate line and the auxiliary capacitance lineare also formed on the gate insulating film 11. The gate electrode WG,the gate line and the auxiliary capacitance line may be formed using thesame material and the same process. The gate electrode WG iselectrically connected with the gate line.

The gate electrode WG of the switching element, the gate line and theauxiliary capacitance line are covered with a first interlayerinsulating film 12. Moreover, the first interlayer insulating film 12 isarranged also on the gate insulating film 11. The gate insulating layerand 11 and the first interlayer insulating film 12 are formed of aninorganic system material, such as silicon oxide and silicon nitride.

A source electrode WS and a drain electrode WD of the switching elementSW are formed on the first interlayer insulating film 12. The sourceline (not shown) is also formed on the first interlayer insulating film12. The source electrode WS, the drain electrode WD, and the sourcelines may be formed using the same process and the same material. Thesource electrode WS is electrically connected with the source line.

The source electrode WS is in contact with the source region SCS of thesemiconductor layer SC through a contact hole which penetrates the gateinsulating film 11 and the first interlayer insulating film 12. Thedrain electrode WD is in contact with the drain region SCD of thesemiconductor layer SC through a contact hole which penetrates the gateinsulating film 11 and the first interlayer insulating film 12. The gateelectrodes WG, the gate lines, the auxiliary capacitance lines, thesource electrode WS, the drain electrode WD, and source lines are formedof electric conductive materials, such as molybdenum, aluminum,tungsten, and titanium, for example.

The switching element SW as described above is covered with a secondinterlayer insulating film 13. That is, the source electrode WS, thedrain electrode WD, and the source lines are covered with the secondinterlayer insulating film 13. Moreover, the second interlayerinsulating film 13 is arranged also on the first interlayer insulatingfilm 12. This second interlayer insulating film 13 is formed of variousorganic materials, such as ultraviolet curing type resin and heat curingtype resin, for example.

The pixel electrode PE is formed on the second interlayer insulatingfilm 13. The pixel electrode PE is connected with the drain electrode WDthrough a contact hole which penetrates the second interlayer insulatingfilm 13. Though the pixel electrode PE is formed by light transmissiveconductive materials, such as Indium Tin Oxide (ITO), Indium Zinc Oxide(IZO), etc, other metals such as aluminum may be used.

In addition, the array substrate AR may be equipped with a portion ofthe common electrode.

A first alignment film AL1 is arranged on a surface of the arraysubstrate AR facing the counter substrate CT, and extends approximatelywhole region of the active area ACT. The first alignment film AL1 coversthe pixel electrode PE, and also formed on the second interlayerinsulating film 13. The first alignment film AL1 is formed of thematerial which shows a lateral alignment characteristics.

On the other hand, the counter substrate CT is formed using a secondtransmissive insulating substrate 20, such as a glass substrate and aplastic substrate. The counter substrate CT includes the commonelectrode CE and a second alignment film AL2 on the surface of thesecond insulating substrate 20 facing the array substrate AR. A blackmatrix arranged facing wiring portions such as the source line S, thegate line G, the auxiliary capacitance line C, and the switching elementSW to define the respective pixels PX, color filter layers arrangedcorresponding to the pixels PX, and an overcoat layer to smooth theconcave and depression of the surface of a black matrix and the colorfilter layer may be formed on the counter substrate CT.

The common electrode CE is formed of the electric conductive materialwhich has light transmissive characteristics, such as ITO and IZO.

A second alignment film AL2 is arranged on a surface of the countersubstrate CT opposing the surface of the array substrate AR, and extendsapproximately whole of the active area ACT. The second alignment filmAL2 covers the common electrodes CE. The second alignment film AL2 isformed materials which have a lateral alignment characteristics

An alignment treatment (for example, rubbing treatment and photoalignment treatment) is performed for making the first and secondalignment films AL1 and AL2 in an initial alignment state. The directionof the first alignment treatment in which the first alignment film AL1carries out the initial alignment of the liquid crystal molecule, andthe direction of the second alignment treatment in which the secondalignment film AL2 carries out the initial alignment of the liquidcrystal molecule, are respectively directions in parallel to the seconddirection Y. The first and second alignment directions are in paralleleach other, and same directions or reverse directions each other.

The array substrate AR and the counter substrate CT as mentioned-aboveare arranged so that the first alignment film AL1 and the secondalignment film AL2 face each other. In this case, the pillar-shapedspacer is formed integrally with one of the substrates by resin materialbetween the first alignment film AL1 on the array substrate AR and thesecond alignment film AL2 on the counter substrate CT. Thereby, apredetermined gap, for example, a 2-7 μm cell gap, is formed, forexample. The array substrate AR and the counter substrate CT are pastedtogether by the seal material which is not illustrated, in which thepredetermined cell gap is formed.

The liquid crystal layer LQ is held at the cell gap formed between thearray substrate AR and the counter substrate CT, and is arranged betweenthe first alignment film AL1 and the second alignment film AL2. Theliquid crystal layer LQ contains the liquid crystal molecule which isnot illustrated. The liquid crystal layer LQ is constituted by positivetype liquid crystal material.

A first optical element OD1 is attached to the external surface of thearray substrate AR, i.e., the external surface of the first insulatingsubstrate 10 which constitutes the array substrate AR by adhesives, etc.The first optical element OD1 contains a first polarizing plate PL1which has a first polarization axis. Moreover, a second optical elementOD2 is attached to the external surface of the counter substrate CT,i.e., the external surface of the second insulating substrate 20 whichconstitutes the counter substrate CT by adhesives, etc. The secondoptical element OD2 contains a second polarizing plate PL2 which has asecond polarization axis. The first polarization axis of the firstpolarizing plate PL1 and the second polarization axis of the secondpolarizing plate PL2 are in a relationship in which they intersectperpendicularly, for example. One polarizing plate is arranged, forexample, so that its polarizing direction is the direction of the longaxis of the liquid crystal molecule, i.e., the first alignment treatmentdirection or a parallel direction to the second alignment treatmentdirection (or in parallel to the second direction Y), or in anorthogonal direction (or in parallel to the first direction X). Thereby,the normally black mode is achieved.

First Embodiment

FIG. 4 is a plan view schematically showing a structure of one pixel ona counter substrate constituting the liquid crystal display panelaccording to a first embodiment.

In this embodiment, the pixel PX corresponds to a region shown with adashed line in the figure, and has the shape of a rectangle whose lengthin the second direction Y is longer than the length in the firstdirection X. For example, the length in the second direction Y of thepixel PX is about 3 times larger than that in the first direction X.

The counter substrate CT includes the common electrode CE at an sideopposing the array substrate which is not illustrated. The commonelectrode CE includes a first sub-common electrode CB1 and a secondsub-common electrode CB2 which extend along the first direction X, and afirst main common electrode CA1 and a second main common electrode CA2extending along the second direction Y.

The first sub-common electrode CB1 and the second sub-common electrodeCB2 extend approximately linearly and are formed in a belt shape. In theillustrated example, the first sub-common electrode CB1 is arrangedalong a bottom end of the pixel PX, and the second sub-common electrodeCB2 is arranged along an upper end of the pixel PX. The first sub-commonelectrode CB1 and the second sub-common electrode CB2 are pulled out tothe outside of the active area, and is electrically connected with anelectric supply portion formed in the array substrate through anelectric conductive component. Thereby, common potential is supplied.

The first main common electrode CA1 and the second main common electrodeCA2 extend substantially linearly and are formed in a belt shape. In theillustrated example, the first main common electrode CA1 is arrangedalong a left-hand side end of the pixel PX, and the second main commonelectrode CA2 is arranged along a right-hand side end of the pixel PX.

The first main common electrode CA1 is connected with the firstsub-common electrode CB1. In the illustrated example, the first maincommon electrode CA1 is connected with the first sub-common electrodeCB1 at the lower left side of the pixel PX, and extends to vicinity ofthe intermediate portion of the pixel PX along the second direction Y.That is, the length in the second direction Y of the first main commonelectrode CA1 is approximately half of the length of the pixel PX in thesecond direction Y. The common electrode CE is not arranged in a regionfrom the intermediate portion of the pixel PX to the second sub-commonelectrode CB2 on the upper left side. Thus, in one PX, a substantially Lcharacter shape is formed with the first main common electrode CA1 andthe first sub-common electrode CB1.

The second main common electrode CA2 is connected with the secondsub-common electrode CB2. In the illustrated example, the second maincommon electrode CA2 is connected with the second sub-common electrodeCB2 on the upper right side of the pixel PX, and extends to vicinity ofthe intermediate portion of the pixel PX along the second direction Y.That is, the length in the second direction Y of the second main commonelectrode CA2 is approximately half of the length in the seconddirection Y of the pixel PX. The common electrode CE is not arranged ina region from the intermediate portion of the pixel PX to the firstsub-common electrode CB1 on the lower right side. Thus, in one PX, asubstantially L character shape is formed with the second main commonelectrode CA2 and the second sub-common electrode CB2.

In addition, the first main common electrode CA1 and the second maincommon electrode CA2 may be connected by a connection electrode CCextending in the first direction X as shown by a dashed line in thefigure. That is, in one PX, the common electrode CE may be formedsubstantially in the shape of a S character.

FIG. 5 is a plan view schematically showing a structure of the pixel atthe array substrate in the liquid crystal display panel when the pixelis seen from the counter substrate side according to the firstembodiment. In addition, in order to explain the positional relationshipof the pixel electrode PE and the common electrode CE, the commonelectrode CE is illustrated with a dashed line. Moreover, onlycomposition required for the explanation in one pixel PX is illustrated,and the illustration of the switching element, etc., is omitted.

The array substrate AR includes a gate line G1 and a gate line G2 whichextend along the first direction X, an auxiliary capacitance line C1arranged between the gate line G1 and the gate line G2 extending alongthe first direction X, a source line S1 and a source line S2 whichextend along the second direction Y, and a pixel electrode PE. Theauxiliary capacitance line C1, the gate line G1, and the gate line G2are formed on the gate insulating film 11, and are covered with thefirst interlayer insulating film 12. The source line S1 and the sourceline S2 are formed on the first interlayer insulating film 12, and arecovered with the second interlayer insulating film 13. The pixelelectrode PE is formed on the second interlayer insulating film 13.

In the illustrated example, the source line S1 is arranged on theleft-hand side end in the pixel PX. Precisely, the source line S1 isarranged striding over a boundary between the illustrated pixel and apixel which adjoins the illustrated pixel PX on its left-hand side. Thesource line S2 is arranged at the right-hand side end in the pixel PX.Precisely, the source line S2 is arranged striding over a boundarybetween the illustrated pixel and a pixel which adjoins the illustratedpixel PX on its right-hand side. Moreover, in the pixel PX, the gateline G1 is arranged at the upper end portion. Precisely, the gate lineG1 is arranged striding over a boundary between the illustrated pixeland a pixel which adjoins the illustrated pixel PX on its upper endside. The gate line G2 is arranged at the lower end portion. Precisely,the gate line G2 is arranged striding over a boundary between theillustrated pixel and a pixel which adjoins the illustrated pixel PX onits lower end side. The auxiliary capacitance line C1 is arranged in theapproximately central portion of the pixel PX.

The pixel electrode PE is arranged between the source line S1 and thesource line S2. Moreover, the pixel electrode PE is arranged between thegate line G1 and the gate line G2. This pixel electrode PE iselectrically connected with the switching element which is not shown.The pixel electrode PE has a sub-pixel electrode PB extending along thefirst direction X, and a first main pixel electrode PA1 and a secondmain pixel electrode PA2 extending along the second direction Y. Thesub-pixel electrode PB, the first main pixel electrode PA1 and thesecond main pixel electrode PA2 are electrically connected each other.In the illustrated example, the sub-pixel electrode PB, the first mainpixel electrode PA1 and the second main pixel electrode PA2 areintegrally or continuously formed.

The sub-pixel electrode PB extends in an approximately straight line,and is formed in a belt shape. In the illustrated example, the sub-pixelelectrode PB extends along the first direction X from the left-hand sideto the right-hand side of the pixel PX. In the sub-pixel electrode PB,one end PBA is located on the left-hand side of the pixel PX, and theother end PBB is located on the right-hand side of the pixel PX.

In addition, in the illustrated example, one end PBA of the sub-pixelelectrode PB does not overlap with the source line S1, and the other endPBB of the sub-pixel electrode PB does not overlap with the source lineS2. However, since the second interlayer insulating film 13 isinterposed between the source lines S1 and S2 and the sub-pixelelectrode PB, one end PBA of the sub-pixel electrode PB may extend onthe source line S1, and the other end PBA of the sub-pixel electrode PBmay extend on the source line S2.

In the illustrated example, the sub-pixel electrode PB is arranged onthe auxiliary capacitance line C1, and functions as a capacitanceportion. Between the sub-pixel electrode PB and the auxiliarycapacitance line C1, the first interlayer insulating film 12 and thesecond interlayer insulating film 13 are disposed as insulating films.That is, rather than the position on the adjoining gate line G1 and thegate line G2, the sub-pixel electrode PB is located inside the pixel PX,and is arranged between the gate line G1 and the gate line G2. Thesub-pixel electrode PB is arranged approximately in the central portionof the pixel PX, and more specifically, is arranged in the position ofapproximately middle of the gate line G1 and the gate line G2. Inaddition, the sub-pixel electrode PB may counter with the gate line.That is, the sub-pixel electrode PB may be arranged on the gate line ina structure in which the gate line is arranged in the approximatelycentral portion of the pixel PX.

The first main pixel electrode PA1 is connected with one end PBA of thesub-pixel electrode PB, and is arranged close to the source line S1. Inthe illustrated example, the first main pixel electrode PA1 is connectedwith the sub-pixel electrode PB in the intermediate portion of the pixelPX, and extends to vicinity of the upper left side of the pixel PX alongthe second direction Y. That is, the first main pixel electrode PA1extends toward upper portion of the pixel PX from the sub-pixelelectrode PB. The length of the first main pixel electrode PA1 in thesecond direction Y is about half of the length of the pixel PX in thesecond direction Y. In one end PBA of the sub-pixel electrode PB, thepixel electrode PE is not arranged from the intermediate portion of thepixel PX to the lower left side. In one pixel PX, the shape of asubstantially L character is made with the first main pixel electrodePA1 and the sub-pixel electrode PB.

In addition, the first main pixel electrode PA1 overlaps with neitherthe source line S1 nor the gate line G1 in the illustrated example.However, the second interlayer insulating film 13 is interposed betweenthe source line S1 and the first main pixel electrode PA1, and the firstinterlayer insulating film 12 and the second interlayer insulating film13 are interposed between the gate line G1 and the first main pixelelectrode PA1. Accordingly, the first main pixel electrode PA1 mayextend on the source line S1 or the gate line G1.

The second main pixel electrode PA2 is connected with the other end PBBof the sub-pixel electrode PB, and is arranged close to the source lineS2. The second main pixel electrode PA2 extends along the seconddirection and in a reverse direction of the extending direction of thefirst main pixel electrode PA1. In the illustrated example, the secondmain pixel electrode PA2 is connected with the sub-pixel electrode PB inthe intermediate portion of the pixel PX, and extends to vicinity of thelower right side of the pixel PX along the second direction Y. That is,the second main pixel electrode PA2 extends toward the lower portion ofthe pixel PX from the sub-pixel electrode PB along the second directionY. The length of the second main pixel electrode PA2 in the seconddirection Y is about half of the length of the pixel PX in the seconddirection Y. In the other end PBB of the sub-pixel electrode PB, thepixel electrode PE is not arranged from the intermediate portion of thepixel PX to the upper right side. In one pixel PX, the shape of asubstantially L character is made with the second main pixel electrodePA2 and the sub-pixel electrode PB.

In addition, the second main pixel electrode PA2 overlaps with neitherthe source line S2 nor the gate line G2 in the illustrated example.However, the second interlayer insulating film 13 is interposed betweenthe source line S2 and the second main pixel electrode PA2, and thefirst interlayer insulating film 12 and the second interlayer insulatingfilm 13 are interposed between the gate line G2 and the second mainpixel electrode PA2. Accordingly, the second main pixel electrode PA2may extend on the source line S2 or the gate line G2.

In the illustrated example, the first sub-common electrode CB1 arrangedon the counter substrate CT and constituting the common electrode CE isarranged at the bottom end portion of the pixel PX, and counters thegate line G2 as shown with a dashed line. That is, the first sub-commonelectrode CB1 is arranged striding over a boundary between theillustrated pixel PX and a pixel which adjoins the illustrated pixel PXon the bottom side. That is, the first sub-common electrode CB1 isarranged in common to the pixels adjoining in the second direction Y, orone first sub-common electrode CB1 is arranged between the adjoiningpixels.

Similarly, the second sub-common electrode CB2 constituting the commonelectrode CE is arranged on the upper end portion of the pixel on thecounter substrate CT, and counters the gate line G1. That is, the secondsub-common electrode CB2 is arranged striding over a boundary betweenthe illustrated pixel and a pixel which adjoins the illustrated pixel PXon the upper side. That is, the second sub-common electrode CB2 isarranged in common to the pixels adjoining in the second direction Y, orone second sub-common electrode CB1 is arranged between the adjoiningpixels.

In addition, in case the auxiliary capacitance lines are arranged on thebottom side and the upper side of the pixel PX, the first sub-commonelectrode CB1 and the second sub-common electrode CB2 may be arranged onthe auxiliary capacitance line. Moreover, as shown by a dashed line inFIG. 5, when the first main common electrode CA1 and the second maincommon electrode CA2 are connected by the connection electrode CC, theconnection electrode CC counters with the sub-pixel electrode PB.

Moreover, the first main common electrode CA1 which constitutes thecommon electrode CE is arranged at the left-hand side end of the pixelPX, and counters a portion of the source line S1. That is, the firstmain common electrode CA1 is arranged striding over the boundary betweenthe illustrated pixel and a pixel which adjoins the illustrated pixel PXon the left-hand side. That is, the first main common electrode CA1 isarranged in common to the pixel which adjoins in the first direction X,or one first main common electrode CA1 is arranged between the adjoiningpixels.

Similarly, the second main common electrode CA2 which constitutes thecommon electrode CE is arranged at the right-hand side end of the pixelPX, and counters a portion of the source line S2. That is, the secondmain common electrode CA2 is arranged striding over the boundary betweenthe illustrated pixel and the pixel which adjoins the illustrated pixelPX on the right-hand side. That is, the second main common electrode CA2is arranged in common to the pixel which adjoins in the first directionX, or one second main common electrode CA2 is arranged between theadjoining pixels.

In the above structure, the first sub-common electrode CB1 and thesecond sub-common electrode CB2 are arranged on the both sides whichsandwich the sub-pixel electrode PB, respectively. That is, thesub-pixel electrode PB is arranged between the first sub-commonelectrode CB1 and the second sub-common electrode CB2. Morespecifically, one sub-pixel electrode PB is located between the firstsub-common electrode CB1 and the second sub-common electrode CB2. Thatis, the first sub-common electrode CB1, the sub-pixel electrode PB, andthe second sub-common electrode CB2 are arranged along the seconddirection Y in this order. The first sub-common electrode CB1, thesub-pixel electrode PB, and the second sub-common electrode CB2 arearranged approximately in parallel. At this time, in a X-Y plane,neither the first sub-common electrode CB1 nor the second sub-commonelectrode CB2 overlaps with the sub-pixel electrode PB. The distancebetween the first sub-common electrode CB1 and the sub-pixel electrodePB in the second direction Y is substantially the same as that betweenthe second sub-common electrode CB2 and the sub-pixel electrode PB.

Moreover, the first main common electrode CA1 extends in a reversedirection of the extending direction of the first main pixel electrodePA1 along the second direction Y on one end PBA side of the sub-pixelelectrode PB. That is, while the first main pixel electrode PA1 extendstoward the upper portion of the pixel PX from one end PBA of thesub-pixel electrode PB, the first main common electrode CA1 extendstoward the bottom portion of the pixel PX from one end PBA of thesub-pixel electrode PB and connected with the first sub-common electrodeCB1. The first main common electrode CA1 and the second main pixelelectrode PA2 are arranged mutually in parallel. At this time, the firstmain common electrode CA1 does not overlap with the second main pixelelectrode PA2 in the X-Y plane.

Similarly, the second main common electrode CA2 extends in a reversedirection of the extending direction of the second main pixel electrodePA2 along the second direction Y on the other end PBB side of thesub-pixel electrode PB. That is, while the second main pixel electrodePA2 extends toward the lower portion of the pixel PX from the other endPBB of the sub-pixel electrode PB, the second main common electrode CA2extends toward the upper portion of the pixel PX from the other end PBBof the sub-pixel electrode PB and connected with the second sub-commonelectrode CB2. The second main common electrode CA2 and the first mainpixel electrode PA1 are arranged mutually in parallel. At this time, thesecond main common electrode CA2 does not overlap with the first mainpixel electrode PA1 in the X-Y plane. The distance between the firstmain common electrode CA1 and the second main pixel electrode PA2 isapproximately the same as that between the second main common electrodeCA2 and the first main pixel electrode PA1 in the first direction X.

In the illustrated example, each of the pixel electrode PE and thecommon electrode CE is formed so as to be symmetry with reference to acenter point O of the pixel PX.

In the bottom half of the pixel, a first aperture OP1 is formed by beingsurrounded with a L character shape common electrode CE and a Lcharacter shape pixel electrode PE. The L character shape commonelectrode CE is formed with the first main common electrode CA1 and thefirst sub-common electrode CB1. The L character shape pixel electrode PEis formed with the second main pixel electrode PA2 and the sub-pixelelectrode PB. The first main common electrode CA1 and the firstsub-common electrode CB1 of the L character shape, and the second mainpixel electrode PA2 and the sub-pixel electrode PB of the L charactershape are respectively symmetry with reference to a central point OB ofthe first aperture.

In the upper half of the pixel, a second aperture OP2 is formed by beingsurrounded with a L character shape common electrode CE and a Lcharacter shape pixel electrode PE. The L character shape commonelectrode CE is formed with the second main common electrode CA2 and thesecond sub-common electrode CB2. The L character shape pixel electrodePE is formed with the second main pixel electrode PA1 and the sub-pixelelectrode PB. The second main common electrode CA2 and the secondsub-common electrode CB2 of the L character shape, and the first mainpixel electrode PA1 and the sub-pixel electrode PB of the L characterare symmetry with reference to the central point OU of the secondaperture, respectively.

In one pixel PX, the area of the first aperture OP1 in the bottom halfand the area of the second aperture OP2 in the upper half areapproximately the same.

FIG. 6 is a plan view of one pixel showing an operation of the liquidcrystal display panel according to the first embodiment.

At the time of non-electric field state, i.e., when a potentialdifference (i.e., electric field) is not formed between the pixelelectrode PE and the common electrode CE, the liquid crystal moleculesLM of the liquid crystal layer LQ are aligned so that their long axisare aligned in a parallel direction with the first alignment directionof the first alignment film AL1 and the second alignment direction ofthe second alignment film AL2 as shown with a dashed line in the figure.In this state, the time of OFF corresponds to the initial alignmentstate, and the alignment direction of the liquid crystal molecule LMcorresponds to the initial alignment direction.

In addition, precisely, the liquid crystal molecules LM are notexclusively aligned in parallel with a X-Y plane, but are pre-tilted inmany cases. For this reason, the precise direction of the initialalignment is a direction in which an orthogonal projection of thealignment direction of the liquid crystal molecule LM at the time of OFFis carried out to the X-Y plane. However, in order to explain simplyhereinafter, the liquid crystal molecule LM is assumed that the liquidcrystal molecule LM is aligned in parallel with the X-Y plane, and isexplained as what rotates in a field in parallel with the X-Y plane.

Here, both of the first alignment treatment direction of the firstalignment film AL1 and the second alignment treatment direction of thesecond alignment film AL2 are directions in parallel to the firstdirection Y. At the time of OFF, the long axis of the liquid crystalmolecule LM is aligned substantially in parallel to the second directionY as shown with a dashed line in the figure. That is, the direction ofthe initial alignment of the liquid crystal molecule LM is in parallelto the second direction Y.

In addition, when both of the first and second alignment treatmentdirections are in parallel, and are reverse directions each other, theliquid crystal molecule LM is aligned so that the liquid crystalmolecule LM is aligned with an approximately same pre-tilt angle nearthe first and second alignment films AL1 and AL2 and in the intermediateportion of the liquid crystal layer LQ (homogeneous alignment). Inaddition, when the respective directions of the alignment treatment ofthe first alignment film AL1 and the second alignment film AL2 are inparallel, and are same directions each other, the liquid crystalmolecule LM is aligned with approximately horizontal direction (i.e.,the pre tilt angle is approximately zero) in a cross-section of theliquid crystal layer LQ. The liquid crystal molecule LM is aligned withthe pre-tilt angle so that the alignment of the liquid crystal moleculeLM near the first alignment film AL1 and the second alignment film AL2becomes symmetrical with respect to the intermediate portion of theliquid crystal layer LQ (splay alignment).

A portion of the back light from the backlight 4 enters into the liquidcrystal display panel LPN after penetrating the first polarizing platePL1. The polarization state of the light which enters into the liquidcrystal display panel LPN changes depending on the alignment state ofthe liquid crystal molecule LM when the light passes the liquid crystallayer LQ. At the time of OFF, the light which passes the liquid crystallayer LQ is absorbed by the second polarizing plate PL2 (black display).

On the other hand, in case where the potential difference is formedbetween the pixel electrode PE and the common electrode CE (at the timeof ON), the lateral electric field in parallel to the substrate (oroblique electric field) is formed between the pixel electrode PE and thecommon electrode CE Thereby, the liquid crystal molecule LM rotateswithin a parallel plane with the substrate surface so that the long axisbecomes in parallel with the direction of the electric field as shown inthe dashed line in FIG. 6.

In the embodiment shown in FIG. 6, one pixel PX is divided into tworegions (i.e., first aperture OP1 and second aperture OP2) with thepixel electrode PE and the common electrode CE. That is, the liquidcrystal molecule LM in the region of the first aperture OP1 rotatesclockwise with respect to the second direction Y, and is aligned so thatthe long axis turns to the lower left in the figure along with electricfield. Moreover, the liquid crystal molecule LM in the region of thesecond aperture OP2 rotates clockwise with respect to the seconddirection Y, and is aligned so that the long axis turns to the upperright in the figure along with electric field.

Thus, in each pixel PX, when the horizontal electric field is formedbetween the pixel electrode PE and the common electrode CE, thealignment direction of the liquid crystal molecule LM is divided into atleast two groups of directions, and two domains are formed correspondingto respective alignment directions. That is, at least two domains areformed in each pixel PX.

At the time of ON, the light which entered into the liquid crystal panelLPN from the backlight 4 enters into the liquid crystal layer LQ. Whenthe back light which entered into the liquid crystal layer LQ passesthrough the first aperture OP1 and the second aperture OP2 divided withthe pixel electrode PE and the common electrode CE, respectively, thepolarization state changes. At the time of ON, at least a portion oflight which passed the liquid crystal layer LQ penetrates the secondpolarizing plate PL2 (white display).

According to this embodiment, it becomes possible to form at least twodomains. Therefore, the viewing angle in at least two directions can becompensated optically, and a wide viewing angle is attained whilebecoming possible to suppress the generation of gradation reversal.Furthermore, it is possible to form two or more domains in one pixelwithout providing other electrodes by arranging the pixel electrode andthe common electrode at the both-end sides which sandwich the apertureof the pixel PX, respectively. Therefore, the shortening of the lengthof the pixel pitch or the shortening of the length of the pixel in thefirst direction X and the second direction Y is possible, and a highresolution pixel can be realized.

Moreover, when assembling shift occurs between the array substrate ARand the counter substrate CT, a difference from a designed value mayarise in distances between the respective common electrodes CE and thepixel electrode PE. However, since the alignment shift is produced incommon to all the pixels PX, there is no difference in the electricfield distribution between the pixels PX, and also no difference in theareas of the apertures among the respective pixels. Thereby, theinfluence to the displayed image is negligible, and it becomes possibleto suppress the variation of the transmissivity due to the assemblingshift.

Accordingly, a high quality liquid crystal display device can besupplied.

Furthermore, at the time of ON, since the lateral electric field ishardly formed (or sufficient electric field to drive the liquid crystalmolecule LM is not formed) near the pixel electrode PE and the commonelectrode CE, the liquid crystal molecule LM hardly moves from theinitial alignment direction like at the time of OFF. For this reason, asmentioned-above, even if the pixel electrode PE and the common electrodeCE are formed of the electric conductive material with the lighttransmissive characteristics in these domains, the backlight hardlypenetrates, i.e., hardly contributes to the display at the time of ON.Therefore, the pixel electrode PE and the common electrode CE do notnecessarily need to be formed of a transparent electric conductivematerial, and may be formed using electric conductive materials, such asaluminum and silver.

Next, the example of a layout is explained according to the firstembodiment.

FIG. 7 is a figure schematically showing an example of the layout of theactive area according to the first embodiment. Herein, only compositionrequired for explanation is illustrated here.

First, when its attention is paid to the shape of the pixel electrode PEof each pixel PX, each pixel electrode PE of two pixels PX which adjoinin the first direction X is line symmetry with respect to a boundarybetween the pixels. In the illustrated example, the shape of the firstpixel electrode PE of a first pixel PX1 is the same as shown in FIG. 5,etc. The shape of the second pixel electrode PE of the second pixel PX2which adjoins on the right-hand side of the first pixel PX1 is linesymmetry with reference to a boundary between the first pixel PX1 andthe second pixel PX2. In addition, the shape of the pixel electrode ofthe pixel which adjoins on the left-hand side of the first pixel PX1 isthe same as the second pixel electrode PE2. That is, the left-lightdirections of the pixel electrode PE are alternately reversed everypixel PX located in a line in the first direction X.

In addition, each pixel electrode PE of two pixels PX which adjoin inthe second direction Y is line symmetry with respect to a boundarybetween pixels. In the illustrated example, the third pixel electrodePE3 of the third pixel PX3 arranged adjacent to the first pixel PX1 onthe lower side is line symmetry with reference to a boundary betweenfirst pixel PX1 and third pixel PX3 and has same shape as the secondpixel electrode PE2 of the second pixel PX2. Though not illustrated, theshape of the pixel electrode adjoining on the upper side of the firstpixel PX1 is also same as that of the second pixel electrode PE2. Thatis, the upper-lower directions of the pixel electrode PE are alternatelyreversed every pixel PX located in a line in the second direction Y.

The common electrode CE is arranged along a boundary between adjacentpixels PX, and includes a L character shape portion which faces the Lcharacter portion of the pixel electrode PE.

In this layout, at the time of ON when the direction of the initialalignment of the liquid crystal molecule LM is set up in the seconddirection Y, and potential difference is formed between the pixelelectrode PE and the common electrode CE of each pixel PX, for example,the long axis of the liquid crystal molecule LM turns to the directionof the upper right shown by an arrow A1 in the upper half of the firstpixel PX1. In the lower half of the first pixel PX1, the long axis ofthe liquid crystal molecule LM turns to the direction of the lower leftshown by an arrow A2. In the upper half of second pixel PX2, the longaxis of the liquid crystal molecule LM turns to the direction of theupper left shown by an arrow A3. The long axis of the liquid crystalmolecule LM turns to the direction of the lower right shown by an arrowA4 in the lower half of the second pixel PX2. The same thing can be saidalso between first pixel PX1 and the third pixel PX3. That is, in twoadjoining pixels PX, it becomes possible to form four domains. In thelayout for a high definition display, since substantially same voltagesare written into the adjacent two pixels PX, it becomes possible tocompensate the viewing angle in four directions optically by the twopixels PX.

FIG. 8 is a figure schematically showing a modification of the layout ofthe active area according to the first embodiment. Herein, onlycomposition required for explanation is illustrated here.

The layout of the pixel electrode PE of each pixel PX shown in FIG. 8 isdifferent compared with the layout shown in FIG. 7 in that each pixelelectrode PE of the pixel PX which adjoins in the second direction Y hasthe same shape.

In the illustrated example, the shape of the second pixel electrode PE2of the second pixel PX2 which adjoins the first pixel PX1 on theright-hand side is line symmetry with a boundary between first pixel PX1and the second pixel PX2. The shape of the pixel electrode which adjoinsthe pixel electrode PE1 of the first pixel PX1 on the left-hand side isthe same as the second pixel electrode PE2. Moreover, the shape of thethird pixel electrode PE3 of the third pixel PX3 which adjoins the firstpixel PX1 on the lower side is the same shape as the first pixelelectrode PE1, and although not illustrated, the shape of the pixelelectrode of the pixel which adjoins the first pixel PX1 on the upperside is the same as the first pixel electrode PE1. That is, the shape ofthe pixel electrode PE of each pixel PX located in a line in the seconddirection Y is the same altogether.

The common electrode CE is arranged along a boundary between adjacentpixels PX, and includes a L character shape portion which faces the Lcharacter portion of the pixel electrode PE.

Also in the above layout, at the time of ON when the direction of theinitial alignment of the liquid crystal molecule LM is set up in thesecond direction Y, and potential difference is formed between the pixelelectrode PE and the common electrode CE of each pixel PX, for example,in the upper half of the first pixel PX1, the long axis of the liquidcrystal molecule LM turns to the direction of the upper right shown byan arrow A1. In the lower half of the first pixel PX1, the long axis ofthe liquid crystal molecule LM turns to the direction of the lower leftshown by an arrow A2. In the upper half of the second pixel PX2, thelong axis of the liquid crystal molecule LM turns to the direction ofthe upper left shown by an arrow A3, and the long axis of the liquidcrystal molecule LM turns to the direction of the lower right shown byan arrow A4 in the bottom half of second pixel PX2. That is, it becomespossible to form four domains in two pixels PX which adjoin in the firstdirection X.

Second Embodiment

FIG. 9 is a plan view schematically showing a structure of one pixel ona counter substrate constituting the liquid crystal display panelaccording to a second embodiment. In the illustrated example, the pixelPX corresponds to a region shown with a dashed line in the figure likethe first embodiment, and has the shape of a rectangle whose length inthe second direction Y is longer than the length in the first directionX. For example, the length in the second direction Y of the pixel PX isabout 3 times larger than that in the first direction X.

The counter substrate CT includes a common electrode CE opposing thearray substrate which is not illustrated. The common electrode CEincludes a first sub-common electrode CB1 and a second sub-commonelectrode CB2 which extend along the first direction X, and a maincommon electrode CA along the second direction Y.

The structures of the first sub-common electrode CB1 and the secondsub-common electrode CB2 are the same as those of the first embodiment.

The main common electrode CA extends in approximately straight line, andis formed in a belt shape. In the illustrated example, the main commonelectrode CA is arranged along the right-hand side of the pixel PX. Themain common electrode CA is connected with the first sub-commonelectrode CB1 and the second sub-common electrode CB2. In theillustrated example, the main common electrode CA is connected with thefirst sub-common electrode CB1 on the lower right side of the pixel PX.The main common electrode CA is also connected with the secondsub-common electrode CB2 on the upper right side of the pixel PX. Inaddition, the common electrode CE is not arranged on the left-hand sideof the pixel PX.

The main common electrode CA and first sub-common electrode CB1 make ashape of L character. Moreover, the main common electrode CA and thesecond sub-common electrode CB2 also make a shape of L character. Themain common electrode CA, the first sub-common electrode CB1 and thesecond sub-common electrode CB2 make a U character shape in one pixelPX.

FIG. 10 is a plan view schematically showing a structure of the pixel onthe array substrate in the liquid crystal display panel when the pixelis seen from the counter substrate side according to the secondembodiment. In addition, in order to explain the positional relationshipbetween the pixel electrode PE and the common electrode CE, the commonelectrode CE is illustrated with a dashed line. Moreover, onlycomposition required for the explanation in the pixel PX is illustrated,and the illustration of a switching element, etc., is omitted.

The array substrate AR is equipped with a gate line G1 and a gate lineG2, the auxiliary capacitance line C1, the source line S1 and the sourceline S2, and the pixel electrode PE like the first embodiment. In thissecond embodiment, the shape of the pixel electrode PE is different ascompared with the first embodiment. The pixel electrode PE has thesub-pixel electrode PB which extends along the first direction X and themain pixel electrode PA which extends along the second direction Y. Thesub-pixel electrodes PB and the main pixel electrode PA are electricallyconnected. In the illustrated example, the sub-pixel electrode PB andthe main pixel electrode PA are integrally or continuously formed.

The sub-pixel electrode PB extends in an approximately line shape, andis formed in a belt shape. In this embodiment, the sub-pixel electrodePB extends along the first direction X from the left-hand side end tothe right-hand side end of the pixel PX. In the sub-pixel electrode PB,one end PBA is located on the left-hand side of the pixel PX, and theother end PBB is located on the right-hand side of the pixel PX.

In the illustrated example, one end PBA of the sub-pixel electrode PBdoes not overlap with the source line S1, and the other end PBB of thesub-pixel electrode PB does not overlap with the source line S2.However, since the second interlayer insulating film 13 is interposedbetween the source lines S1 and S2 and the sub-pixel electrode PB, oneend PBA of the sub-pixel electrode PB may extend on the source line S1,and the other end PBA of the sub-pixel electrode PB also may extend onthe source line S2.

Moreover, in the illustrated example, the sub-pixel electrode PB isarranged on the auxiliary capacitance line C1, and functions as acapacitance portion. Between the sub-pixel electrode PB and theauxiliary capacitance line C1, the first interlayer insulating film 12and the second interlayer insulating film 13 are interposed asinsulating films. The sub-pixel electrode PB is located inside the pixelPX rather than the respective positions on the adjoining gate line G1and the gate line G2, and is arranged between the gate line G1 and thegate line G2. The sub-pixel electrode PB is arranged in theapproximately central portion of the pixel PX, and, more specifically,is arranged in the position of approximately middle between the gateline G1 and the gate line G2. In addition, the sub-pixel electrode PBmay counter with the gate line in a structure in which the gate line isarranged in the approximately central portion of the pixel PX.

The main pixel electrode PA is connected with one end PBA of thesub-pixel electrode PB at the intermediate portion, and arranged closeto the source line S1. In the illustrated example, the main pixelelectrode PA extends from near the lower left side to near the upperleft side of the pixel PX along the second direction Y. The main pixelelectrode PA is connected with the sub-pixel electrode PB in theintermediate portion of the main pixel electrode PA. That is, the mainpixel electrode PA extends toward the both sides of the sub-pixelelectrode PB. The length of the main electrode PA in the seconddirection Y is substantially the same as that of the pixel PX. The mainpixel electrode is not arranged on the other end PBB side of thesub-pixel electrode PB.

In one pixel PX, the shape of T character is made with the main pixelelectrode PA and the sub-pixel electrode PB. In addition, on both sidesof the sub-pixel electrode PB, the shape of L character is made with themain pixel electrode PA and the sub-pixel electrode PB on the lower sideof the pixel PX, and similarly, the shape of L character is similarlymade with the main pixel electrode PA and the sub-pixel electrode PB onthe upper side of the pixel PX.

In the illustrated example, the main pixel electrode PA overlap withneither the source line nor the gate lines G1 and G2 However, since thesecond interlayer insulating film 13 is interposed between the sourceline S1 and the main pixel electrode PA, and further, between the gatelines G1 and G2 and the main pixel electrode PA, the first interlayerinsulating film 12 and the second interlayer insulating film 13 areinterposed, a portion of the main pixel electrodes PA may extend on thesource line S1 or the gate lines G1 and G2.

In the illustrated example, the first sub-common electrode CB1 formed onthe counter substrate CT and constituting the common electrode CE isarranged at the bottom portion of the pixel PX like the firstembodiment, and faces the gate line G2 as shown with the dashed line.The second sub-common electrode CB2 is arranged at the upper portion ofthe pixel PX, and counters the gate line G1.

Moreover, the main common electrode CA which constitutes the commonelectrode CE is arranged at the right-hand side end of the pixel PX, andcounters a portion of the source line S2. That is, the main commonelectrode CA is arranged striding over a boundary between theillustrated pixel PX and the pixel which adjoins the illustrated pixelPX on the right-hand side. That is, the main common electrode CA isarranged between the adjoining pixels in common to the pixel whichadjoins in the first direction X, i.e., the pixel PX on the right-handside. One main common electrode CA is arranged between the adjacentpixels.

In this embodiment, the first sub-common electrode CB1 and the secondsub-common electrode CB2 are arranged on the both sides of the sub-pixelelectrode PB, respectively. That is, the sub-pixel electrode PB isarranged between the first sub-common electrode CB1 and the secondsub-common electrode CB2. More specifically, one sub-pixel electrode PBis located between the first sub-common electrode CB1 and the secondsub-common electrode CB2. That is, the first sub-common electrode CB1,the sub-pixel electrode PB, and the second sub-common electrode CB2 arearranged along the second direction Y in this order. The firstsub-common electrode CB1, the sub-pixel electrode PB, and the secondsub-common electrode CB2 are arranged in parallel each other. At thistime, in the X-Y plane, neither the first sub-common electrode CB1 northe second sub-common electrode CB2 overlaps with the sub-pixelelectrode PB. The distance between the first sub-common electrode CB1and the sub-pixel electrode PB in the second direction Y issubstantially same as that between the second sub-common electrode CB2and the sub-pixel electrode PB.

The main common electrode CA extends along the second direction Y on theother end PBB side of the sub-pixel electrode PB. That is, while themain pixel electrode PA extends along the second direction Y from thebottom portion to the upper portion of the pixel PX on one end PBA sideof the sub-pixel electrode PB and is connected with the sub-pixelelectrode PB, the main common electrode CA extends from bottom portionto the upper portion of the pixel PX in the second direction Y on theother end PBB side of the sub-pixel electrode PB, and is connected withthe first sub-common electrode CB1 and the second sub-common electrodeCB2. The main common electrode CA and the main pixel electrode PA arearranged approximately in parallel. At this time, the main commonelectrode CA does not overlap with the main pixel electrode PA in theX-Y plane.

In the bottom half of the pixel, a first aperture OP1 is formed by beingsurrounded with a L character shape common electrode CE and a Lcharacter shape pixel electrode PE. The L character shape commonelectrode CE is formed with the first main common electrode CA and thefirst sub-common electrode CB1. The L character shape pixel electrode PEis formed with the main pixel electrode PA and the sub-pixel electrodePB. The first main common electrode CA and the first sub-commonelectrode CB1 of the L character shape, and the main pixel electrode PAand the sub-pixel electrode PB of the L character shape are pointsymmetry with reference to the central point OB of a first aperture OP1,respectively.

In the upper half of the pixel, a second aperture OP2 is formed by beingsurrounded with a L character shape common electrode CE and a Lcharacter shape pixel electrode PE. The L character shape commonelectrode CE is formed with the main common electrode CA and the secondsub-common electrode CB2. The L character shape pixel electrode PE isformed with the main pixel electrode PA and the sub-pixel electrode PB.The main common electrode CA and the second sub-common electrode CB2 ofthe L character shape, and the main pixel electrode PA and the sub-pixelelectrode PB of the L character shape is point symmetry with referenceto the central point OU of a second aperture OP2, respectively.

In one pixel PX, the area of the first aperture OP1 of the bottom halfportion and the area of the second aperture OP2 of the upper halfportion are approximately the same.

FIG. 11 is a plan view of one pixel showing an operation of the liquidcrystal display panel according to the second embodiment.

At the time of OFF, like the first embodiment, the liquid crystalmolecule LM of the liquid crystal layer LQ aligns so that the long axisof the liquid crystal molecule may turn to the first alignment treatmentdirection of the first alignment film AL1 and the second alignmenttreatment direction of the second alignment film AL2 shown with a dashedline in the figure, herein, in a substantially parallel direction to thesecond direction Y. At this OFF time, the black images are displayed.

At the time of ON in which potential difference is formed between thepixel electrode PE and the common electrode CE, lateral electric fieldin parallel to the substrate or oblique electric field is formed betweenthe pixel electrode PE and the common electrodes CE. Thereby, the liquidcrystal molecule LM rotates within the parallel plane to the substrateso that the long axis aligns with the direction of electric field asshown with a dashed line in the figure.

In this embodiment, one pixel PX is divided into two domains firstaperture OP1 and second aperture OP2) defined by the pixel electrode PEand the common electrode CE. That is, the liquid crystal molecule LM inthe domain of the first aperture OP1 rotates counterclockwise withreference to the second direction Y so that the long axis may turn tothe lower right side in the figure along with electric field. Moreover,the liquid crystal molecule LM in the domain of the second aperture OP2rotates clockwise with reference to the second direction Y so that thelong axis may turn to the upper right side in the figure along with theelectric field.

Thus, in each pixel PX, when the lateral electric field or the obliqueelectric field is formed between the pixel electrode PE and the commonelectrode CE, the alignment direction of the liquid crystal molecule LMis divided into at least two groups of directions, and two domains areformed corresponding to respective alignment directions. That is, atleast two domains are formed in each pixel PX. At the time of ON, whiteimage is displayed.

According to the second embodiment, the same effect as the firstembodiment is acquired.

Next, one example of the layout is explained about the above-mentionedsecond embodiment.

FIG. 12 is a figure schematically showing an example of the layout ofthe active area according to the second embodiment. In addition, onlythe structure required for explanation is illustrated here.

First, when its attention is paid to the shape of the pixel electrode PEof each pixel PX, each pixel electrode PE of two pixels PX which adjoinin the first direction X is line symmetry with reference a the boundarybetween the pixels. In the illustrated example, the shape of the firstpixel electrode PE1 of the first pixel PX1 is the same as shown in FIG.10. The shape of the second pixel electrode PE2 of the second pixel PX2which adjoins the first pixel PX1 on the right-hand side is linesymmetry with reference to a boundary between the first pixel PX1 andthe second pixel PX2. In addition, the shape of the pixel electrode ofthe pixel which adjoins the first pixel PX1 on the left-hand side isalso the same as the second pixel electrode PE2. That is, the left-rightdirections of the pixel electrode PE are alternately reversed everypixel PX located in a line in the first direction X.

Moreover, in the illustrated example, the shape of a third pixelelectrode PE3 of a third pixel PX3 which adjoins the first pixel PX1 onthe bottom side is the same as the second pixel electrode PE2 of thesecond pixel PX2. Although not illustrated, the pixel electrode of thepixel which adjoins the first pixel PX1 on the upper portion is also thesame as the second pixel electrode PE2. That is, the upper-downdirections of the pixel electrode are alternately reversed every thepixel electrode PE of each pixel PX located in a line in the seconddirection Y.

The common electrode CE is arranged along a boundary between adjacentpixels PX, and includes a L character shape portion which faces the Lcharacter portion of the pixel electrode PE.

In the above layout, at the time of ON when the direction of the initialalignment of the liquid crystal molecule LM is set up in the seconddirection Y, and potential difference is formed between the pixelelectrode PE and the common electrode CE of each pixel PX, for example,the long axis of the liquid crystal molecule LM turns to the directionof the upper right shown by an arrow A1 in the upper half of the firstpixel PX1. In the lower half of the first pixel PX1, the long axis ofthe liquid crystal molecule LM turns to the direction of the lower rightshown by an arrow A2. In the upper half of second pixel PX2, the longaxis of the liquid crystal molecule LM turns to the direction of theupper left shown by an arrow A3. The long axis of the liquid crystalmolecule LM turns to the direction of the lower left shown by an arrowA4 in the lower half of second pixel PX2. The same thing can be saidalso between the first pixel PX1 and the third pixel PX3. That is, intwo adjoining pixels PX, it becomes possible to form four domains.

FIG. 13 is a figure schematically showing a modification of the layoutof the active area according to the second embodiment. In addition, onlythe structure required for explanation is illustrated here.

The layout shown here is different as compared with the layout shown inFIG. 12 in that each pixel electrode PE of the pixel PX which adjoins inthe second direction Y has the same shape.

In the illustrated example, the second pixel electrode PE2 of the secondpixel PX2 which adjoins the first pixel PX1 on the right-hand side isline symmetry with reference to a boundary between the first pixel PX1and the second pixel PX2. The shape of the pixel electrode which adjoinsthe first pixel electrode PE1 of the first pixel PX1 on the left-side isalso the same as the second pixel electrode PE2. Moreover, the shape ofthe third pixel electrode PE3 of the third pixel PX3 which adjoins thefirst pixel PX1 on the lower side is the same as the first pixelelectrode PE1, and although not illustrated, the shape of the pixelelectrode of the pixel which adjoins the first pixel PX1 on the upperside is also the same as the first pixel electrode PE1. That is, thepixel electrode PE of each pixel PX located in a line in the seconddirection Y is the same shape altogether.

The common electrode CE is arranged along a boundary between adjacentpixels PX, and includes a L character shape portion which faces the Lcharacter portion of the pixel electrode PE.

Also in the above layout, at the time of ON when the direction of theinitial alignment of the liquid crystal molecule LM is set up in thesecond direction Y, and potential difference is formed between the pixelelectrode PE of each pixel PX and the common electrode CE, for example,in the upper half of the first pixel PX1, the long axis of the liquidcrystal molecule LM turns to the direction of the upper right shown byan arrow A1. In the lower half of the first pixel PX1, the long axis ofthe liquid crystal molecule LM turns to the direction of the lower rightshown by an arrow A2. In the upper half of the second pixel PX2, thelong axis of the liquid crystal molecule LM turns to the direction ofthe upper left shown by an arrow A3, and the long axis of the liquidcrystal molecule LM turns to the direction of the lower left shown by anarrow A4 in the bottom half of second pixel PX2. That is, it becomespossible to form four domains in two pixels PX which adjoin in the firstdirection X.

As explained above, according to the embodiments, it becomes possible tooffer the high quality liquid crystal display device.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other shapes; furthermore, variousomissions, substitutions and changes in the shape of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such shapes or modifications as would fall within the scope andspirit of the inventions.

1. A liquid crystal display device having a plurality of pixels,comprising: a first substrate including; a sub-pixel electrode extendingin a first direction, a first main pixel electrode connected with oneend of the sub-pixel electrode and extending in a second directionorthogonally crossing the first direction, and a second main pixelelectrode connected with the other end of the sub-pixel electrode andextending in the second direction opposite to the extending direction ofthe first main pixel electrode, a second substrate including; a firstsub-common electrode and a second sub-common electrode arranged on bothsides sandwiching the sub-pixel electrode, a first main common electrodeconnected with the first sub-common electrode and extending along thesecond direction opposite to the extending direction of the first mainpixel electrode on one end side of the sub-pixel electrode, and a secondmain common electrode connected with the second sub-common electrode andextending along the second direction opposite to the extending directionof the second main pixel electrode on the other end side of thesub-pixel electrode, a liquid crystal layer including liquid crystalmolecules and held between the first substrate and the second substrate.2. The liquid crystal display device according to claim 1, wherein thefirst substrate further includes a first source line and a second sourceline arranged on both sides sandwiching the first and second main pixelelectrodes and the sub-pixel electrode, and extending in the seconddirection, and the first and second main common electrodes respectivelyface the first and second source lines and are arranged in commonbetween adjoining pixels in the first direction.
 3. The liquid crystaldisplay device according to claim 1, wherein the first substrate furtherincludes a gate line and an auxiliary capacitance line extending in thefirst direction, and the sub-pixel electrode faces the gate line or thecapacitance line through an insulating film.
 4. The liquid crystaldisplay device according to claim 3, wherein the first sub-commonelectrode and the second sub-common electrode face the gate line or thecapacitance line and are arranged in common between adjacent pixels inthe second direction.
 5. The liquid crystal display device according toclaim 1, wherein the shapes of respective pixel electrodes of a firstpixel and a second pixel adjoining each other in the first direction isline symmetry with reference to a boundary between the first pixel andthe second pixel.
 6. The liquid crystal display device according toclaim 5, wherein the shape of a pixel electrode of a third pixeladjoining the first pixel in the second direction is the same as that ofthe second pixel.
 7. The liquid crystal display device according toclaim 5, wherein the shape of a pixel electrode of a third pixeladjoining the first pixel in the second direction is the same as that ofthe first pixel.
 8. The liquid crystal display device according to claim1, wherein an initial alignment direction of the liquid crystal moleculeis a direction in parallel with the second direction.
 9. The liquidcrystal display device according to claim 1, wherein the pixel includesa first aperture surrounded by the first main common electrode, thefirst sub-common electrode, the sub-pixel electrode and the second mainpixel electrode, and a second aperture surrounded by the second maincommon electrode, the second sub-common electrode, the sub-pixelelectrode and the first main pixel electrode.
 10. The liquid crystaldisplay device according to claim 9, wherein the area of the firstaperture is substantially the same as that of the second aperture.
 11. Aliquid crystal display device having a plurality of pixels, comprising:a first substrate including; a sub-pixel electrode extending in a firstdirection, and a main pixel electrode connected with one end of thesub-pixel electrode at the intermediate portion thereof and extending ina second direction orthogonally crossing the first direction, a secondsubstrate including; a first sub-common electrode and a secondsub-common electrode arranged on both sides sandwiching the sub-pixelelectrode and extending in the first direction, and a main commonelectrode connected with the first sub-common electrode and the secondsub-common electrode and extending in the second direction on the otherend side of the sub-pixel electrode, a liquid crystal layer includingliquid crystal molecules and held between the first substrate and thesecond substrate.
 12. The liquid crystal display device according toclaim 11, wherein the first substrate further includes a first sourceline and a second source line arranged on both sides sandwiching themain pixel electrode and the sub-pixel electrode and extending in thesecond direction, the main pixel electrode is arranged close to thefirst source line, and the main common electrode faces the second sourceline and are arranged in common between adjacent pixels in the firstdirection.
 13. The liquid crystal display device according to claim 11,wherein the first substrate further includes a gate line and anauxiliary capacitance line extending in the first direction, and thesub-pixel electrode faces the gate line or the capacitance line throughan insulating film.
 14. The liquid crystal display device according toclaim 13, wherein the first sub-common electrode and the secondsub-common electrode face the gate line or the capacitance line and arearranged in common between adjacent pixels in the second direction. 15.The liquid crystal display device according to claim 11, wherein theshapes of respective pixel electrodes of a first pixel and a secondpixel adjoining each other in the first direction is line symmetry withreference to a boundary between the first pixel and the second pixel.16. The liquid crystal display device according to claim 15, wherein theshape of a pixel electrode of a third pixel adjoining the first pixel inthe second direction is the same as that of the second pixel.
 17. Theliquid crystal display device according to claim 15, wherein the shapeof a pixel electrode of a third pixel adjoining the first pixel in thesecond direction is the same as that of the first pixel.
 18. The liquidcrystal display device according to claim 11, wherein an initialalignment direction of the liquid crystal molecule is a direction inparallel with the second direction.
 19. The liquid crystal displaydevice according to claim 11, wherein the pixel includes a firstaperture surrounded by the main common electrode, the first sub-commonelectrode and the sub-pixel electrode and the main pixel electrode, anda second aperture surrounded by the main common electrode, the secondsub-common electrode, the sub-pixel electrode and the main pixelelectrode.
 20. The liquid crystal display device according to claim 19,wherein the area of the first aperture is substantially the same as thatof the second aperture.